Optical sensor and image forming apparatus equipped therewith

Abstract

To provide an optical sensor that can suppress an increase in the area of ​​the mounting region. [Solution] The optical sensor comprises a circuit board, a plurality of electronic components arranged in a mounting area, and a cover member covering the light-emitting element and the light-receiving element, wherein the cover member has a first support and a second support, the circuit board has a first through-hole into which the first support is inserted and a second through-hole into which the second support is inserted, the mounting area has a first end, a second end opposite to the first end, a first region located on the side of a first direction from a center line extending in the opposite direction between the first end and the second end, and a second region located on the side of a second direction opposite to the first direction from the center line, the first through-hole located on the first end side of the second region, the second through-hole located on the side of the second end of the first region, and the largest of the plurality of electronic components is located on the side of the first end of the first region.

Description

Technical Field

[0001] The present disclosure relates to an optical sensor and an image forming apparatus including the same.

Background Art

[0002] An optical sensor including a light emitting element that emits measurement light to irradiate a measurement object and a light receiving element that receives reflected light of the measurement light is known. The optical sensor is used, for example, for detecting a patch image for measuring toner density and color shift formed on an intermediate transfer belt of a tandem type image forming apparatus. Patent Document 1 discloses a light emitting / receiving element module including a wiring board, a light emitting element and a light receiving element disposed on the upper surface of the wiring board, and a lens member having a plurality of support columns. The plurality of support columns include a plurality of first support columns and a plurality of second support columns. Each of the plurality of first support columns is in contact with the upper surface of the wiring board. Each of the plurality of second support columns is disposed in a plurality of holes disposed in the wiring board.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described light emitting / receiving element module, there may be a case where a mounting area for arranging a plurality of electronic components is formed on the lower surface of the wiring board. At this time, in addition to the plurality of electronic components, the plurality of holes in which the plurality of second support columns are disposed are also disposed in the mounting area, so that the area of the mounting area may increase.

[0005] An object of the present disclosure is to provide an optical sensor capable of suppressing an increase in the area of a mounting area.

Means for Solving the Problems

[0006] An optical sensor according to one aspect of the present disclosure comprises a circuit board having a first surface and a second surface opposite to the first surface, a light-emitting element and a light-receiving element disposed on the first surface, a plurality of electronic components disposed in a rectangular mounting area on the second surface, and a cover member covering the light-emitting element and the light-receiving element, wherein the cover member has a first support and a second support, the circuit board has a first through-hole into which the first support is inserted and a second through-hole into which the second support is inserted, the mounting area has a first end, a second end opposite to the first end, a first region disposed on the side of a first direction from a center line extending in the opposite direction between the first end and the second end, and a second region disposed on the side of a second direction opposite to the first direction from the center line, the first through-hole disposed on the side of the second end of the second region, and the largest of the plurality of electronic components disposed on the side of the first end of the first region.

[0007] An image forming apparatus relating to another aspect of the present disclosure comprises an image forming unit that forms an image, and the above-described optical sensor that irradiates light onto the image formed by the image forming unit and detects predetermined characteristics. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide an optical sensor that can suppress an increase in the area of ​​the mounting region, and an image forming apparatus equipped with the optical sensor. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic cross-sectional view showing the internal structure of a color printer to which the optical sensor of this disclosure is applied. [Figure 2] Figure 2 is a cross-sectional view showing a part of an optical sensor according to one embodiment of the present disclosure. [Figure 3] Figures 3(A) and (B) are perspective views showing the external appearance of a part of an optical sensor according to one embodiment of the present disclosure. [Figure 4]Figure 4(A) is a top view of a portion of the optical sensor shown in Figure 3, Figure 4(B) is a bottom view, and Figure 4(C) is a side view. [Figure 5] Figure 5 is a cross-sectional view of the VV line in Figure 4(B). [Figure 6] Figure 6 is a plan view of a concentration sensor according to one embodiment of the present disclosure. [Figure 7] Figure 7 is a side view of a concentration sensor according to one embodiment of the present disclosure. [Figure 8] Figure 8 is a bottom view of a concentration sensor according to one embodiment of the present disclosure. [Figure 9] Figure 9 is a bottom view of a concentration sensor according to a modified embodiment of the present disclosure. [Modes for carrying out the invention]

[0010] The optical sensor of this disclosure will be described below with reference to the drawings. The optical sensor of this disclosure is a module that measures the physical properties of an object by irradiating it with measurement light and receiving the reflected light. There are no particular restrictions on the object to be measured, and it can be a solid, semi-solid, liquid, powder, etc. There are also no particular restrictions on the physical properties to be measured, as long as they can be analyzed from the reflected light. For example, the optical sensor of this disclosure is suitable for measuring the color and density of an object to be measured. In the embodiment described below, an optical sensor assembled into a color printer for detecting the density of toner for image formation will be given as an example.

[0011] [Description of color printer] First, the configuration of a color printer to which the optical sensor of this disclosure is applied will be described. Figure 1 is a schematic cross-sectional view showing the internal structure of a tandem-type color printer 1. The color printer 1 includes image forming units (image forming sections) 2Y, 2C, 2M, 2Bk, an optical scanning device 23, an intermediate transfer unit 28, and a fuser unit 29, all housed in a main body housing 10. An output tray 11 is provided on the top surface of the main body housing 10. A sheet output port 12 opens opposite the output tray 11. A manual feed tray 13 is provided on the side wall of the main body housing 10, and a paper feed cassette 14 for storing sheets for automatic feeding, etc., is provided at the bottom of the main body housing 10.

[0012] The image forming units 2Y, 2C, 2M, and 2Bk are units that form toner images of yellow, cyan, magenta, and black, respectively, and are arranged in tandem at predetermined intervals in the horizontal direction. Each image forming unit 2Y, 2C, 2M, and 2Bk includes a photoreceptor drum 21 having a circumferential surface for carrying an electrostatic latent image and a toner image, a charger 22 for charging the circumferential surface of the photoreceptor drum 21, a developer 24 for depositing developer onto the electrostatic latent image to form a toner image, toner containers 25Y, 25C, 25M, and 25Bk for supplying toner of each color to the developer 24, a primary transfer roller 26 for primary transfer of the toner image formed on the photoreceptor drum 21, and a cleaning device 27 for removing residual toner from the circumferential surface of the photoreceptor drum 21. The optical scanning device 23 scans the circumferential surface of each color photoreceptor drum 21 with a beam in the main scanning direction, and forms an electrostatic latent image on the circumferential surface for forming a toner image.

[0013] The intermediate transfer unit 28 performs primary transfer of the toner image formed on the photoreceptor drum 21. The intermediate transfer unit 28 includes a transfer belt 281 that rotates while contacting the circumferential surface of each photoreceptor drum 21, and a driving roller 282 and a driven roller 283 over which the transfer belt 281 is stretched. The toner images on the photoreceptor drums 21 of each color are superposed at the same position on the transfer belt 281 and subjected to primary transfer. Thereby, a full-color toner image is formed on the transfer belt 281. Opposite the driving roller 282, a secondary transfer roller 15 is disposed that forms a secondary transfer nip portion T across the transfer belt 281. The full-color toner image on the transfer belt 281 is secondarily transferred onto the sheet at the secondary transfer nip portion T.

[0014] The fixing unit 29 includes a fixing roller 291 with a built-in heat source, and a pressure roller 292 that forms a fixing nip portion N together with the fixing roller 291. The fixing unit 29 performs a fixing process of welding the toner to the sheet by heating and pressing the sheet onto which the toner image has been transferred at the secondary transfer nip portion T at the fixing nip portion N. The sheet subjected to the fixing process is discharged from the sheet discharge port 12 toward the paper discharge tray 11.

[0015] Inside the main body housing 10, a density sensor 16 is disposed. The density sensor 16 is an example of the "optical sensor" of the present disclosure. The density sensor 16 is disposed to face the outer circumferential surface of the transfer belt 281 that carries the toner image in the vicinity of the secondary transfer nip portion T. The density sensor 16 optically detects the density of the toner image formed on the transfer belt 281 and converts it into an electrical signal.

[0016] [Detection Principle of Toner] FIG. 2 is a cross-sectional view showing the density sensor 16 according to the present embodiment. The density sensor 16 includes a sensor substrate 3, a lens unit 4, a first light shielding wall 51, and a second light shielding wall 52. The measurement object of the density sensor 16 is a toner patch printed on the toner-carrying surface 28T of the transfer belt 281.

[0017] The sensor substrate 3 includes a substrate 30 having a mounting surface 3M and an element group 3E arranged in a row on the mounting surface 3M. The element group 3E includes a first light emitting and receiving pair 31 for detecting black toner and a second light emitting and receiving pair 32 for detecting color toner. The first light emitting and receiving pair 31 consists of a first light emitting element 33 and a first light receiving element 34 arranged at a predetermined interval on the mounting surface 3M. The second light emitting and receiving pair 32 consists of a second light emitting element 35 and a second light receiving element 36 arranged at a predetermined interval on the mounting surface 3M at a position different from that of the first light emitting and receiving pair 31.

[0018] The first light emitting element 33 and the second light emitting element 35 are LEDs (Light Emitting Diodes) that emit light of a predetermined wavelength. The first light receiving element 34 and the second light receiving element 36 are PDs (Photo Diodes) that output a current according to the amount of received light. Each element of the element group 3E is arranged linearly. Specifically, each element of the element group 3E is arranged in a row on the mounting surface 3M in the order of the first light emitting element 33, the first light receiving element 34, the second light receiving element 36, and the second light emitting element 35. Each element of the element group 3E does not necessarily have to be arranged strictly linearly, and may be an array in a row including an offset that can be regarded as linear.

[0019] The lens unit 4 is arranged in front of the mounting surface 3M, that is, between the sensor substrate 3 and the toner carrying surface 28T. The lens unit 4 includes a first lens unit 41, a second lens unit 42, a third lens unit 43, and a fourth lens unit 44 as lens parts for condensing light. The lens parts are located between the optical paths of the light emitting elements and the light receiving elements. On the optical path of the first light emitting and receiving pair 31, the first lens unit 41 is arranged in front of the first light emitting element 33, and the second lens unit 42 is arranged behind the first light receiving element 34. On the optical path of the second light emitting and receiving pair 32, the third lens unit 43 is arranged in front of the second light emitting element 35, and the fourth lens unit 44 is arranged behind the second light receiving element 36. The lens unit 4 further includes a holder part 40 that holds each lens part.

[0020] The first lens unit 41 focuses the light emitted by the first light-emitting element 33 to create a first measurement light L11 that is spot-illuminated at a predetermined position on the toner-carrying surface 28T. The second lens unit 42 focuses the specularly reflected light L2 of the first measurement light L11 from the toner-carrying surface 28T and guides it to the first light-receiving element 34. In other words, the first light-receiving element 34 is positioned to receive the specularly reflected light L2. The third lens unit 43 focuses the light emitted by the second light-emitting element 35 to create a second measurement light L12 that is spot-illuminated at a predetermined position on the toner-carrying surface 28T. The fourth lens unit 44 focuses the diffusely reflected light L3 of the second measurement light L12 from the toner-carrying surface 28T and guides it to the second light-receiving element 36. The second light-receiving element 36 is positioned to receive the light image of the diffusely reflected light L3 created by the fourth lens unit 44.

[0021] The first light-shielding wall 51 and the second light-shielding wall 52 are opaque materials that do not allow light to pass through. The first light-shielding wall 51 is positioned in front of the mounting surface 3M between the first light-emitting element 33 and the first light-receiving element 34. The first light-shielding wall 51 prevents light emitted from the first light-emitting element 33 from going directly to the first light-receiving element 34 without passing through the toner-carrying surface 28T. In other words, it prevents light before it is focused by the first lens portion 41 from being received by the first light-receiving element 34. The second light-shielding wall 52 is positioned in front of the mounting surface 3M between the second light-emitting element 35 and the second light-receiving element 36. The second light-shielding wall 52 prevents light emitted from the second light-emitting element 35 from going directly to the second light-receiving element 36. In other words, it prevents light before it is focused by the third lens portion 43 from being received by the second light-receiving element 36.

[0022] An open space OS is provided in front of the mounting surface 3M between the first light-receiving pair 31 and the second light-receiving pair 32, and in this embodiment, between the first light-receiving element 34 and the second light-receiving element 36. The open space OS is a non-light-shielding space in which there are substantially no light-shielding members. The open space OS is partitioned by the first light-shielding wall 51, the second light-shielding wall 52 and the lens unit 4. Note that the open space OS does not have to be a perfect space, and may contain small protrusions or structures that do not affect the optics.

[0023] [Description of some of the external appearance of the concentration sensor (external appearance of the sensor board, lens unit, and housing)] Figure 3(A) is a bottom perspective view showing a part of the external appearance of the concentration sensor 16 according to this embodiment, and Figure 3(B) is a top perspective view. Figure 4(A) is a top view of a part of the concentration sensor 16, Figure 4(B) is a bottom view, and Figure 4(C) is a side view.

[0024] The density sensor 16 includes the aforementioned sensor substrate 3, lens unit 4, and housing 6. The lens unit 4 and housing 6 each correspond to an example of a "cover member" in this disclosure. As shown in Figure 4(B), the sensor substrate 3 includes a substrate 30 and a group of elements 3E mounted on the substrate 30. As described above, the group of elements 3E includes a first light-receiving pair 31 for detecting black toner and a second light-receiving pair 32 for detecting color toner. The group of elements 3E is arranged in a line in the order of a first light-emitting element 33, a first light-receiving element 34, a second light-receiving element 36, and a second light-emitting element 35.

[0025] The lens unit 4 includes a lens portion 4R that focuses light and a holder portion 40 that holds the lens portion 4R. As described above, the lens portion 4R includes a first lens portion 41, a second lens portion 42, a third lens portion 43, and a fourth lens portion 44 (see Figure 2). These four lens portions 41, 42, 43, and 44 are arranged in the direction of the arrangement of the element group 3E and constitute a lens mass. The holder portion 40 has a rectangular parallelepiped shape that surrounds the lens mass, and the upper surface of the holder portion 40 is recessed in the portion of the lens mass.

[0026] The lens unit 4 includes a pair of first pillars 45 and a pair of second pillars 46 for positioning the lens portion 4R. For example, each of the pair of first pillars 45 and the pair of second pillars 46 is cylindrical. The pair of first pillars 45 and the pair of second pillars 46 protrude from the lower surface of the holder portion 40. Each first pillar 45 and each second pillar 46 extends from the lens portion 4R toward the circuit board 70 described later. Each first pillar 45 is projected near one diagonal corner of the rectangular lens unit 4. Each second pillar 46 is provided near the other diagonal corner of the lens unit 4 and is a convex portion that protrudes less from the lower surface of the holder portion 40 than the first pillars 45. The first pillars 45 are mainly positioning projections for the lens unit 4 in the horizontal direction (along the substrate). The second pillars 46 are positioning projections for the lens unit 4 in the height direction.

[0027] The housing 6 is a rectangular parallelepiped housing that includes a bottom plate 61 and side plates 62 and has a cavity capable of housing the lens unit 4. The lens unit 4 is fitted into the housing 6. The bottom plate 61 faces the bottom surface of the lens unit 4. The side plates 62 are erected from the periphery of the bottom plate 61 and cover the sides of the lens unit 4. The bottom plate 61 and the side plates 62 are bonded and fixed together at the outer circumference of the bottom plate 61, forming a single unit.

[0028] [Description of some internal structures of the concentration sensor (light-shielding wall and lens unit)] Figure 5 is a cross-sectional view of the VV line in Figure 4(B). The lens unit 4 is fitted into the housing 6 such that the lens portion 4R covers the bottom plate 61 on the sensor substrate 3. The first light-shielding wall 51 has a smaller protrusion height from the bottom plate 61 than the second light-shielding wall 52. For this reason, the lens portion 4R, which is positioned to straddle the first light-shielding wall 51 and the second light-shielding wall 52, is inclined so that the side facing the first light-shielding wall 51 is lower. The four lens portions 41, 42, 43, and 44 of the lens portion 4R each have a convex lens surface on both the upper and lower sides of the lens unit 4.

[0029] Figure 5 shows the state in which the first measurement light L11 and the second measurement light L12 are emitted from the density sensor 16 to the density detection position DP where the object to be measured TG is printed on the toner-carrying surface 28T of the transfer belt 281. It also shows the state in which specular reflected light L2 and diffuse reflected light L3 from the object to be measured TG are incident on the density sensor 16. As previously described, the object to be measured TG is black toner BT and color toner CT.

[0030] The first lens section 41 is positioned opposite the first aperture 613 of the bottom plate 61. The first lens section 41 collects the light emitted from the first light-emitting element 33 and passing through the first aperture 613, and irradiates the density detection position DP as the first measurement light L11. The second lens section 42 and the fourth lens section 44 are positioned opposite the third aperture 615 via an open space OS. The second lens section 42 collects the specularly reflected light L2 of the first measurement light L11 from the density detection position DP and directs it into the first photodetector 34. The first light-shielding wall 51 blocks the light emitted from the first light-emitting element 33 that is directed directly towards the first photodetector 34.

[0031] The third lens section 43 is positioned opposite the second aperture 614. The third lens section 43 collects the light emitted from the second light-emitting element 35 and passing through the second aperture 614, and irradiates the density detection position DP with the second measurement light L12. The fourth lens section 44 collects a portion of the diffusely reflected light generated at the density detection position DP of the second measurement light L12 and directs it onto the second photodetector 36 as diffusely reflected light L3. The second light-shielding wall 52 blocks the light emitted from the second light-emitting element 35 that is directed directly towards the second photodetector 36.

[0032] In this embodiment, the arrangement order of the element group on the sensor substrate 3 is the arrangement order shown in Figure 2 above. Therefore, specular reflected light L2 and diffuse reflected light L3 pass through the open space OS. In the open space OS, that is, between the first light-shielding wall 51 and the second light-shielding wall 52, there are substantially no objects that reflect light. Therefore, it is difficult for unnecessary reflected light to be generated between the first light-shielding wall 51 and the second light-shielding wall 52. Accordingly, it is possible to suppress stray light other than the specular reflected light L2 or diffuse reflected light L3 that should be detected from entering the first light-receiving element 34 or the second light-receiving element 36. Note that other arrangement orders of element group 3E different from the above may also be applied to this embodiment. For example, each element of element group 3E may be arranged in a line on the mounting surface 3M in the order of first light-receiving element 34, first light-emitting element 33, second light-receiving element 36, and second light-emitting element 35.

[0033] [Description of the remaining part of the concentration sensor (the circuit board)] Next, the substrate portion 7 of the concentration sensor 16 will be described in detail. In addition to the sensor substrate 3, lens unit 4, and housing 6 described above, the concentration sensor 16 further comprises the substrate portion 7. Figure 6 is a plan view of the concentration sensor 16 according to this embodiment. Figure 7 is a side view of the concentration sensor 16 according to one embodiment of the present disclosure. Figure 8 is a bottom view of the concentration sensor 16 according to one embodiment of the present disclosure. In Figures 6 to 8, the directional relationships will be explained using mutually orthogonal XYZ Cartesian coordinates. One side in the X direction will be referred to as the "+X side," and the other side opposite to the one side in the X direction will be referred to as the "-X side." One side in the Y direction will be referred to as the "+Y side," and the other side opposite to the one side in the Y direction will be referred to as the "-Y side." One side in the Z direction will be referred to as the "+Z side," and the other side opposite to the one side in the Z direction will be referred to as the "-Z side."

[0034] Figures 6 to 8 show the X, Y, and Z directions, respectively. These directions are shown for convenience to explain the structure of the concentration sensor 16 according to this embodiment and do not limit the manner in which the concentration sensor 16 can be used according to this disclosure. The -Y direction corresponds to an example of the "first direction" in this disclosure. The +Y direction corresponds to an example of the "second direction" in this disclosure. The X direction corresponds to an example of the "opposing direction" in this disclosure. The Z direction corresponds to an example of the "thickness direction" in this disclosure.

[0035] The substrate section 7 is mounted with multiple electronic components for operating each element of the sensor board 3, and multiple contact pads 73. The multiple electronic components include an IC chip 71, a connector 72, capacitors, resistors, etc. The IC chip 71 is an example of a "control IC (integrated circuit)" as disclosed herein. Although other electronic components (capacitors, resistors, etc.) smaller than the IC chip 71 and connector 72 are also mounted on the substrate section 7, their description is omitted here. As shown in Figures 6 to 8, the substrate section 7 has a circuit board 70, an IC chip 71 mounted on the circuit board 70, a connector 72, and multiple contact pads 73.

[0036] The circuit board 70 consists of a rectangular plate-like member extending in a predetermined longitudinal direction. In this embodiment, the predetermined longitudinal direction is the X direction. The circuit board 70 has dimensions that extend longer on both sides than the housing 6 described above. The circuit board 70 has a first surface S1 and a second surface S2 which is the surface opposite to the first surface S1 in the thickness direction. The first surface S1 and the second surface S2 are surfaces that extend in the longitudinal direction and the width direction of the circuit board 70. In this embodiment, the width direction is the Y direction. In other words, the first surface S1 and the second surface S2 are arranged on opposite sides of each other in the Z direction.

[0037] As an example, the circuit board 70 is made of epoxy glass. The circuit board 70 also has wiring 81 arranged inside the circuit board 70 or on the second surface S2. The wiring 81 is electrically connected to the circuit pattern of the substrate 30, the IC chip 71, the connector 72, and the multiple contact pads 73. In other words, the wiring 81 electrically connects the first light-emitting element 33, the first light-receiving element 34, the second light-emitting element 35, the second light-receiving element 36, the IC chip 71, the connector 72, and the multiple contact pads 73.

[0038] Furthermore, the circuit board 70 is divided into four areas: a first component mounting area M1, a second component mounting area M2, a first component mounting prohibited area N1, and a second component mounting prohibited area N2. More specifically, each of the first surface S1 and the second surface S2 of the circuit board 70 further includes a first component mounting area M1, a second component mounting area M2, a first component mounting prohibited area N1, and a second component mounting prohibited area N2. These areas are arranged from the -X side to the +X side in the order of second component mounting area M2, first component mounting prohibited area N1, first component mounting area M1, and second component mounting prohibited area N2. The first component mounting area M1 on the second surface S2 is an example of a "mounting area" in this disclosure.

[0039] The circuit board 70 has a first visual pattern 70A, a second visual pattern 70B, and a third visual pattern 70C formed on it. For example, the circuit board 70 is made of a green substrate, and each of the first visual pattern 70A, the second visual pattern 70B, and the third visual pattern 70C is a white linear portion applied to the substrate. Note that each of the first visual pattern 70A, the second visual pattern 70B, and the third visual pattern 70C may be a groove or the like formed on the circuit board 70.

[0040] The first visual pattern 70A, the second visual pattern 70B, and the third visual pattern 70C are arranged in the X direction in that order. The area between the second visual pattern 70B and the third visual pattern 70C corresponds to the first component mounting area M1. The area between the first visual pattern 70A and the second visual pattern 70B corresponds to the first component mounting prohibited area N1. The area located in the +X direction relative to the placement position of the third visual pattern 70C on the circuit board 70 corresponds to the second component mounting prohibited area N2. Furthermore, the area located in the -X direction relative to the placement position of the first visual pattern 70A on the circuit board 70 corresponds to the second component mounting area M2.

[0041] [Description of the first component mounting area M1 on the first surface S1] Here, we will mainly describe the first component mounting area M1 on the first surface S1. As described above, the sensor substrate 3 includes a substrate 30 and a group of elements 3E mounted on the substrate 30. The substrate 30 consists of a rectangular plate-like member extending in the X direction. The first light-emitting element 33, the first light-receiving element 34, the second light-emitting element 35, and the second light-receiving element 36 are arranged in the X direction (see Figure 4(B)). The sensor substrate 3 is mounted on the first surface S1 of the circuit board 70, approximately in the center of the first component mounting area M1. As shown in Figure 8, the shape of the first component mounting area M1 is, for example, rectangular. Specifically, the shape of the first component mounting area M1 is a rectangle that is long in the X direction of the circuit board 70. The area of ​​the first component mounting area M1 is larger than the area of ​​the sensor substrate 3.

[0042] A circuit pattern for mounting the element group 3E is printed on the mounting surface 3M of the substrate 30. The light-receiving element and light-emitting element constituting the element group 3E are mounted on the circuit pattern. In other embodiments of the substrate 30 according to this disclosure, a sensor substrate 3 may be used in which a semiconductor substrate such as a silicon substrate is used as the element group 3E, and each element is directly formed on the semiconductor substrate. Alternatively, the element group 3E may be mounted on a circuit board 70 instead of on the substrate 30.

[0043] The housing 6 covers the sensor substrate 3. As described above, the housing 6 includes a bottom plate 61 and side plates 62. The housing 6 is mounted on the first component mounting area M1 on the first surface S1 of the circuit board 70. As a result, as shown in Figure 7, the housing 6 protrudes from the first surface S1 of the circuit board 70 by the height HA of the bottom plate 61 and side plates 62 in the +Z direction. The housing 6 houses the lens unit 4. As shown in Figure 6, it is preferable that the size of the housing 6 on a plane perpendicular to the Z direction is equal to the area of ​​the first component mounting area M1. As described above, the lens unit 4 mainly includes a pair of first support columns 45 which are positioning protrusions in the X and Y directions (direction along the substrate) of the lens unit 4, and a pair of second support columns 46 which are positioning protrusions in the Z direction of the lens unit 4 (see Figure 3(B)).

[0044] A pair of first support columns 45 and a pair of second support columns 46 are arranged in a predetermined area within the first component mounting area M1. Specifically, the diameters of the first support columns 45 and the second support columns 46 are less than half the length of the first component mounting area M1 in the Y direction. Furthermore, one of the pair of first support columns 45 and the other of the pair of first support columns 45 are separated by a predetermined distance in the X direction. One of the pair of second support columns 46 and the other of the pair of second support columns 46 are separated by a predetermined distance in the X direction. The predetermined distance is, for example, the dimension of the sensor substrate 3 in the X direction.

[0045] [Description of the first component mounting area M1 on the second surface S2] Next, referring to Figure 8, we will mainly explain the first component mounting area M1 of the second surface S2. The first component mounting area M1 has a first end E1 located on the -X side and extending along the Y direction, and a second end E2 located on the +X side and extending along the Y direction. In Figure 8, a center line CL is shown extending in the X direction at the center of the first component mounting area M1 in the Y direction. The first component mounting area M1 has a first region MM1 located on the -Y side of the center line CL, and a second region MM2 located on the +Y side of the center line CL. In other words, the first component mounting area M1 is divided into two regions of equal area.

[0046] A first hole K1 and a second hole K2 are formed in the first component mounting area M1 so as to penetrate from the first surface S1 to the second surface S2. The first hole K1 is an example of the "first through hole" of this disclosure. The second hole K2 is an example of the "second through hole" of this disclosure. For example, the first hole K1 is circular, and the second hole K2 is formed in the shape of an elongated hole along the X direction of the circuit board 70. The tip of the first support column 45 is inserted through each of the first hole K1 and the second hole K2. The inner diameter of the first hole K1 and the inner diameter of the second hole K2 in the short direction are set to correspond to the outer diameter of the tip of the first support column 45.

[0047] The first hole K1 is formed on the side of the first end E1 of the second region MM2. Specifically, the first hole K1 is formed near the first end E1 of the second region MM2 within the first component mounting region M1. On the other hand, the second hole K2 is formed on the side of the second end E2 of the first region MM1. Specifically, the second hole K2 is formed near the second end E2 of the first region MM1 within the first component mounting region M1. As a result, the first hole K1 restrains one of the pair of first support pillars 45 in the XY direction along the surface of the circuit board 70, and the second hole K2 restrains the other of the pair of first support pillars 45 in the Y direction of the circuit board 70, thereby positioning the lens unit 4.

[0048] Furthermore, on the first surface S1, a pair of contact portions K3 are formed in the first component mounting area M1. Each contact portion K3 is a part of the first surface S1 of the circuit board 70. The contact portions K3 may be positioned with a slight step relative to the first surface S1. Also, one of the pair of contact portions K3 is formed on the first end E1 side of the first area MM1. Specifically, one of the pair of contact portions K3 is formed near the first end E1 of the first area MM1 within the first component mounting area M1. On the other hand, the other of the pair of contact portions K3 is formed on the second end E2 side of the second area MM2. Specifically, the other of the pair of contact portions K3 is formed near the second end E2 of the second area MM2 within the first component mounting area M1. Each contact portion K3 is positioned in the Z direction by contact with the tip surface of the second support column 46.

[0049] [Explanation of IC chip] Next, the IC chip 71 for operating each element of the sensor board 3 will be described. The IC chip 71 controls each element of the sensor board 3. The IC chip 71 includes an integrated circuit, which is a core chip 711, and leads 712. The IC chip 71 is located on the first component mounting area M1 of the second surface S2. Specifically, the IC chip 71 is located on the first end E1 side of the first region MM1. More specifically, the IC chip 71 is located near the first end E1 of the first region MM1 within the first component mounting area M1 of the second surface S2.

[0050] The IC chip 71 is the largest component among the multiple electronic components arranged on the first component mounting area M1. More specifically, the IC chip 71 is the largest component among the multiple electronic components arranged on the first component mounting area M1 in a plane perpendicular to the Z direction. In the Y direction, the dimensions of the IC chip 71 are less than half the length of the first component mounting area M1.

[0051] The IC chip 71 is fixed to the circuit board 70 via leads 712. The leads 712 are electrically connected to the wiring 81 of the circuit board 70. Specifically, the leads 712 are mounted on a land formed in the first component mounting area M1 of the second surface S2 and are electrically connected to the wiring 81 of the circuit board 70. Here, a sensor substrate 3, etc., is located in the first component mounting area M1 of the first surface S1 opposite to the first component mounting area M1 of the second surface S2. If the electronic component were to be fixed to the first component mounting area M1 of the second surface S2 by wire bonding using ultrasound, the ultrasound would be transmitted to and dispersed by the sensor substrate 3, etc. As a result, the strength with which the electronic component is fixed to the first component mounting area M1 of the second surface S2 may be insufficient with wire bonding. However, in this embodiment, the IC chip 71, which is an electronic component mounted on the second surface S2, is fixed to the first component mounting area M1 of the second surface S2 by a method different from wire bonding. Therefore, it is possible to suppress the issue of insufficient strength in fixing the IC chip 71 to the first component mounting area M1 on the second surface S2.

[0052] Other IC chips different from those described above may be applied to this embodiment. For example, the IC chip may be mounted on the circuit board 70 using the COB (Chip On Board) method and electrically connected by wire bonding. Furthermore, the IC chip may be placed on the circuit board via Ag paste and electrically connected by wire bonding using wires. Subsequently, a coating layer may be formed to cover the multiple wires and the IC chip.

[0053] As described above, in this embodiment, the first hole K1 is located on the first end E1 side of the second region MM2, the second hole K2 is located on the second end E2 side of the first region MM1, and the largest IC chip 71 among the multiple electronic components located in the first component mounting region M1 is located on the first end E1 side of the first region MM1. In other words, neither the IC chip 71, the first hole K1, nor the second hole K2 exist in the central part of the first component mounting region M1 or on the second end E2 side of the second region MM2. As a result, other electronic components can be placed in the central part of the first component mounting region M1 and on the second end E2 side of the second region MM2. Therefore, it is possible to suppress the need to increase the area of ​​the first component mounting region M1 in order to place other electronic components.

[0054] [Description of connector] Next, the connector 72 for operating each element of the sensor board 3 will be described. The connector 72 accepts the mating connector terminals (not shown) extending from the main body housing 10 of the color printer 1, and enables the supply of drive voltage and the transmission and reception of various electrical signals between the main body housing 10 and the density sensor 16. The connector 72 is, for example, a block-type terminal block. On the other hand, the mating connector terminals are, for example, detachable connection connectors to the block-type terminal block.

[0055] The connector 72 is located in the second component mounting area M2 on the first surface S1 of the circuit board 70. In other words, the connector 72 is not located in the first component mounting area M1 on the second surface S2. The connector 72 is a larger electronic component than the IC chip 71. Specifically, in the XY plane perpendicular to the Z direction, the area of ​​the connector 72 is larger than the area of ​​the IC chip 71. Also, in the Z direction, the height HB of the connector 72 is higher than the height HC of the IC chip 71.

[0056] As a result of the connector 72 being located in a different area from the first component mounting area M1 on the second surface S2, it is possible to suppress an increase in the area of ​​the first component mounting area M1 on the second surface S2. Furthermore, the IC chip 71 is located on the first end E1 side of the first area MM1, which is relatively close to the second component mounting area M2. Therefore, even if the connector 72 is not located in the first component mounting area M1, the connector 72 and the IC chip 71 can be electrically connected over a short distance. As a result, it is possible to suppress noise from entering the electrical signals (information writing signals, light intensity calibration signals, etc.) from the connector 72 to the IC chip 71.

[0057] Specifically, the connector 72 is electrically connected to the wiring 81 of the circuit board 70. The connector 72 has a housing 721 and a number of legs 723 protruding from the housing 721. For example, the housing 721 is a rectangular parallelepiped housing.

[0058] The connector 72 is fixed to the circuit board 70 via a plurality of legs 723. Each of the plurality of legs 723 is electrically connected to the wiring 81 of the circuit board 70. Specifically, each of the plurality of legs 723 is inserted into a hole formed in the first surface S1 of the circuit board 70 and electrically connected to the wiring 81 of the circuit board 70. In other words, the connector 72 is fixed to the circuit board 70 in a way different from wire bonding. In addition, the portion of the plurality of legs 723 on the first surface S1 is covered with a sealing material 82. The sealing material 82 must be non-conductive and is formed, for example, from silicone resin. Note that although an example has been shown in which each of the plurality of legs 723 of the connector 72 is inserted into a hole formed in the first surface S1 of the circuit board 70, it is not limited to this. For example, each of the plurality of legs 723 of the connector 72 may be placed on the wiring 81 of the circuit board 70 to which solder paste has been applied and then soldered by reflow soldering.

[0059] The housing 721 has a connection surface 722 to which the mating connector terminals are connected. The connection surface 722 is oriented in the -X direction. The connection surface 722 has a detachment opening 724. The mating connector terminals are detached from the detachment opening 724. The detachment opening 724 is open and oriented in the -X direction. The detachment opening 724 is, for example, a rectangular parallelepiped-shaped hole. As a result, since the direction in which the mating connector terminals are detached from the connector 72 is parallel to the first surface S1, it is possible to suppress the tilting of the circuit board 70 relative to the main housing 10 (transfer belt 281) of the color printer 1.

[0060] A method for fixing the density sensor 16 to the main body housing 10 of the color printer 1 will now be described. The circuit board portion 7 further has fixing holes H1 and notches H2. The circuit board portion 7 is fixed to the main body housing 10 of the color printer 1 by the fixing holes H1 and notches H2 (see Figure 1). In detail, fixing bolts, screws, etc. are inserted through the fixing holes H1 and notches H2, respectively, when the density sensor 16 is fixed to the main body housing 10 of the color printer 1.

[0061] The fixing hole H1 is formed in the first component mounting prohibited area N1. The fixing hole H1 penetrates in the Z direction. The fixing hole H1 is a circular opening in the circuit board 70. The fixing hole H1 is located on the circuit board 70 on the -X direction side (outside) from the first component mounting area M1.

[0062] On the other hand, the notch H2 is formed in the second component mounting prohibited area N2. The notch H2 is a U-shaped notch with an open portion at the +X side edge of the circuit board 70. In other words, the notch H2 is open on the +X side. As a result, there is a degree of freedom in the position of the concentration sensor 16 relative to the main housing 10, and the concentration sensor 16 can be easily fixed to the main housing 10. Furthermore, after the substrate portion 7 is fixed to the main housing 10, the notch H2 acts as a buffer against thermal expansion of the circuit board 70, suppressing warping of the circuit board 70.

[0063] In detail, the first component mounting prohibited area N1 and the second component mounting prohibited area N2 on the first surface S1 side of the circuit board 70 are brought into contact with the wall of the main housing 10, and fixing bolts, screws, etc. are inserted from the second surface S2 side of the circuit board 70 into the fixing holes H1 and notches H2, respectively. As a result, the circuit board portion 7 is installed relative to the main housing 10 with the first surface S1 of the circuit board 70 as the height reference. In other words, the element group 3E of the circuit board portion 7 is installed relative to the object to be measured TG with the first surface S1 of the circuit board 70 as the height reference. Therefore, it is possible to suppress the effect of errors due to the thickness of the circuit board 70 on the detection accuracy of the element group 3E.

[0064] [Description of contact lens pads] Next, with reference to Figure 8, the multiple contact pads 73 will be described in detail. In addition to the IC chip 71, multiple contact pads 73 are formed on the substrate portion 7. Each of the multiple contact pads 73 is located in the first component mounting area M1 on the second surface S2 of the circuit board 70. Each of the multiple contact pads 73 is, for example, a circular conductor. Each of the multiple contact pads 73 is electrically connected to the wiring 81.

[0065] The multiple contact pads 73 include, for example, a first pad 73a, a second pad 73b, a third pad 73c, a fourth pad 73d, and a fifth pad 73e. The first pad 73a is electrically connected to the connector 72 via wiring 81. Before fixing the density sensor 16 to the main body housing 10 of the color printer 1, an inspector can test whether the connector 72 and the sensor board 3 are electrically connected by touching the first pad 73a with a probe or the like.

[0066] The second pad 73b is electrically connected to the lead 712 of the IC chip 71 via wiring 81. Before fixing the density sensor 16 to the main housing 10 of the color printer 1, the inspector can send and receive electrical signals (information writing signals, light intensity calibration signals, etc.) to and from the IC chip 71C by touching the second pad 73b with a probe or the like. The third pad 73c, fourth pad 73d, and fifth pad 73e are also electrically connected to other electronic components. The inspector can use the third pad 73c, fourth pad 73d, and fifth pad 73e to test the electrical connection status.

[0067] The first pad 73a, the second pad 73b, and the third pad 73c are positioned in the center of the first component mounting area M1 on the second surface S2. In other words, neither the IC chip 71, the first hole K1, nor the second hole K2 exist in the center of the first component mounting area M1 on the second surface S2. Therefore, the first pad 73a, the second pad 73b, and the third pad 73c can be formed in the center of the first component mounting area M1 on the second surface S2. As a result, it is possible to suppress the need to increase the area of ​​the first component mounting area M1 on the second surface S2 in order to form the first pad 73a, the second pad 73b, and the third pad 73c. ​​Furthermore, because the first pad 73a, the second pad 73b, and the third pad 73c are positioned in the center of the first component mounting area M1 on the second surface S2, the inspector can easily perform tests.

[0068] The fourth pad 73d and the fifth pad 73e are positioned on the second end E2 side of the second region MM2 of the first component mounting area M1 on the second surface S2. Specifically, the fifth pad 73e is positioned near the second end E2 of the second region MM2 within the first component mounting area M1 on the second surface S2. In other words, since neither the IC chip 71, the first hole K1, nor the second hole K2 exist on the second end E2 side of the second region MM2, the fourth pad 73d and the fifth pad 73e can be positioned there. This means that the area of ​​the first component mounting area M1 can be reduced by utilizing the empty space in the first component mounting area M1 to position the fourth pad 73d and the fifth pad 73e. Furthermore, the inspector can perform testing without interference with the IC chip 71.

[0069] Furthermore, in this embodiment, the color printer 1 includes an image forming unit that forms an image, and a density sensor 16 (light sensor) that irradiates light onto the image formed by the image forming unit and detects predetermined characteristics. With this configuration, the area of ​​the first component mounting area M1 is kept from becoming too large, so the density sensor 16 can be placed in a small space within the main housing 10 of the image forming unit.

[0070] The density sensor 16 (optical sensor) and the color printer 1 equipped therewith have been described above, but the disclosure is not limited thereto.

[0071] [Description of modified embodiments] Figure 9 is a bottom view of the circuit board 70 of the substrate portion 7M of the concentration sensor 16M according to a modified embodiment of the present disclosure. Figure 9 shows an example in which the connector 72 is arranged in the first component mounting area M1 of the second surface S2.

[0072] The circuit board 70 is divided into three areas: a first component mounting area M1, a first component mounting prohibited area N1, and a second component mounting prohibited area N2. In other words, the circuit board 70 does not have a second component mounting area M2.

[0073] The connector 72 and the IC chip 71 are located on the first component mounting area M1 of the second surface S2. The connector 72 is located on the first end E1 side of the first area MM1. The connector 72 is the largest component among the multiple electronic components located on the first component mounting area M1 of the second surface S2.

[0074] The IC chip 71 is located on the second end E2 side of the second region MM2. The IC chip 71 is the second largest component among the multiple electronic components located on the first component mounting region M1 of the second surface S2.

[0075] The first hole K1 is located on the first end E1 side of the second region MM2, and the second hole K2 is located on the second end E2 side of the first region MM1. The largest connector 72 among the multiple electronic components located in the first component mounting region M1 of the second surface S2 is located on the first end E1 side of the first region MM1. In other words, neither the connector 72, the first hole K1, nor the second hole K2 exist in the central part of the first component mounting region M1 of the second surface S2, nor on the second end E2 side of the second region MM2. As a result, other electronic components can be placed in the central part of the first component mounting region M1 of the second surface S2, and on the second end E2 side of the second region MM2. Therefore, it is possible to suppress the need to increase the area of ​​the first component mounting region M1 of the second surface S2 in order to place other electronic components.

[0076] Furthermore, in this embodiment, the second largest IC chip 71 among the multiple electronic components arranged in the first component mounting area M1 of the second surface S2 is positioned on the second end E2 side of the second area MM2. In other words, since neither the connector 72, the first hole K1, nor the second hole K2 exist on the second end E2 side of the second area MM2, the IC chip 71 can be placed there. As a result, it is possible to suppress the need to increase the area of ​​the first component mounting area M1 of the second surface S2 in order to place the IC chip 71. [Explanation of Symbols]

[0077] 1. Color printer 10 Main Housing 16. Concentration sensor (light sensor) 3. Sensor board (sensor part) 3E element group 3M mounting surface 30 circuit boards 31, 32 First light-receiving pair, second light-receiving pair 33, 34 First light-emitting element, first photodetector 35, 36 Second light-emitting element, second photodetector 4. Lens unit (cover component) 45 1st pillar 46 Second pillar 6. Housing (cover component) 61 Bottom plate 7 circuit boards 70 Circuit boards 71 IC chips (electronic components) 72 Connectors (Electronic Components) 721 cabinet 722 terminals 723 Connection surface 724 Detachment port CL center line E1 1st end E2 2nd end H1 fixing hole H2 Notch K1 1st hole (1st through hole) K2 2nd hole (2nd through hole) K3 Abutted part M1 First component mounting area (mounting area) MM1 1st area MM2 2nd area S1 page 1 S2 side 2

Claims

1. A circuit board having a first surface and a second surface opposite to the first surface, A light-emitting element and a light-receiving element arranged on the first surface, Multiple electronic components arranged in a rectangular mounting area on the second surface, A cover member that covers the light-emitting element and the light-receiving element, Equipped with, The cover member has a first support column and a second support column, The circuit board has a first through-hole into which the first support column is inserted, and a second through-hole into which the second support column is inserted. The mounting region has a first end, a second end opposite to the first end, a first region located on the side of the first direction from the center line extending in the opposite direction between the first and second ends, and a second region located on the side of the second direction opposite to the first direction from the center line. The first through hole is located on the first end side of the second region, The second through hole is located on the second end side of the first region, The largest of the plurality of electronic components is a light sensor located on the first end side of the first region.

2. The circuit board further has fixing holes located on the circuit board outside the first end of the mounting area, The optical sensor according to claim 1, wherein the fixing hole penetrates the circuit board in the thickness direction.

3. The circuit board further has a notch located on the circuit board outside the second end of the mounting area, The optical sensor according to claim 1, wherein the notch is open toward the edge of the circuit board along the opposing direction.

4. The connector further comprises a connector having a connection surface to which the mating connector is connected, The connector is electrically connected to the light-emitting element and the light-receiving element, The optical sensor according to claim 1, wherein the connector is arranged on the first surface of the circuit board outside the first end of the mounting area.

5. The aforementioned circuit board is Multiple pads arranged in the aforementioned mounting area, Wiring electrically connected to each of the plurality of pads, the light-emitting element, the light-receiving element, and the plurality of electronic components. The optical sensor according to claim 4, further comprising the above.

6. The plurality of electronic components include a control IC that controls the light-emitting element and the light-receiving element. The plurality of pads include a first pad and a second pad, The control IC is the largest of the plurality of electronic components, The first pad is electrically connected to the connector via the wiring, The optical sensor according to claim 5, wherein the second pad is electrically connected to the leads of the control IC via the wiring.

7. The largest of the plurality of electronic components is located near the first end of the first region. The optical sensor according to claim 5, wherein at least one of the plurality of pads is located in the center of the mounting area.

8. The largest of the plurality of electronic components is located near the first end of the first region. The optical sensor according to claim 5, wherein at least one of the plurality of pads is located near the second end of the second region.

9. The optical sensor according to claim 1, wherein each of the plurality of electronic components is mounted on the second surface of the circuit board in a manner different from wire bonding.

10. An image forming unit that forms an image, The optical sensor according to claim 1, which irradiates light onto the image formed by the image forming unit and detects predetermined characteristics, An image forming apparatus comprising:

Images